You can vibe code an entire mess and it'll still "work". We've seen this already. As good as LLMs are they still write overly verbose, sloppy and often inefficient code. But if it works, most people won't care - and won't notice the security flaws that are going to be rife in such large, and frankly mostly unread, codebases.
Honestly I think the security world is primed for it's most productive years.